.\" Copyright (c) 2010 Kai Wang
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.Dd April 11, 2010
.Os
.Dt DWARF_ATTRLIST 3
.Sh NAME
.Nm dwarf_attrlist
.Nd retrieve DWARF attribute descriptors
.Sh LIBRARY
.Lb libdwarf
.Sh SYNOPSIS
.In libdwarf.h
.Ft int
.Fo dwarf_attrlist
.Fa "Dwarf_Die die"
.Fa "Dwarf_Attribute **attrbuf"
.Fa "Dwarf_Signed *attrcount"
.Fa "Dwarf_Error *err"
.Fc
.Sh DESCRIPTION
Function
.Fn dwarf_attrlist
retrieves the DWARF attribute descriptors associated with a
debugging information entry descriptor in argument
.Ar die .
The descriptors are returned as an array of values of the opaque type
.Vt Dwarf_Attribute .
The data associated with each returned attribute descriptor may be
queried using the form query functions in the
.Xr dwarf 3
API set.
.Pp
Argument
.Ar attrbuf
points to a location that will hold a pointer to the returned
array of DWARF attribute descriptors.
Argument
.Ar attrcount
points to a location that will hold the number of descriptors in
the returned array.
.Pp
If argument
.Ar err
is non-NULL, it is used to return an error descriptor in case of an
error.
.Ss Memory Management
In the current implementation, the memory allocated for each DWARF
attribute descriptor and for the returned array of descriptors is
managed by the library and the application does not need to explicitly
free the returned pointers.
However, for compatibility with other implementations of the
.Xr dwarf 3
API, the application is permitted to pass the pointers returned by to
the
.Fn dwarf_dealloc
function.
.Sh RETURN VALUES
Function
.Fn dwarf_attrlist
returns
.Dv DW_DLV_OK on success.
.Pp
If the debugging information entry descriptor denoted by argument
.Ar die
does not contain any attribute, the function returns
.Dv DW_DLV_NO_ENTRY
and sets argument
.Ar err .
For other errors, it returns
.Dv DW_DLV_ERROR
and sets argument
.Ar err .
.Sh EXAMPLES
To retrieve the attribute list for a DWARF debugging information
entry use:
.Bd -literal
	Dwarf_Die dw_die;
	Dwarf_Error dw_e;
	Dwarf_Unsigned dw_count;
	Dwarf_Attribute *dw_attributes;
	int error, i;

	\&... variable dw_die contains a reference to the DIE of interest ...

	/* Retrieve the attribute list from the DIE. */
	if ((error = dwarf_attrlist(dw_die, &dw_attributes, &dw_count,
		&dw_e)) != DW_DLV_OK)
		errx(1, "dwarf_attrlist: %s", dwarf_errmsg(dw_e));

	/* Process the attribute list. */
        for (i = 0; i < dw_count; ++i) {
		/* Use the returned pointers in dw_attributes[i] here. */
        }
}
.Ed
.Sh ERRORS
Function
.Fn dwarf_diename
can fail with the following errors:
.Bl -tag -width ".Bq Er DW_DLE_ARGUMENT"
.It Bq Er DW_DLE_ARGUMENT
Arguments
.Ar die ,
.Ar attrbuf ,
or
.Ar attrcount
were NULL.
.It Bq Er DW_DLE_NO_ENTRY
Argument
.Ar die
had no attributes.
.It Bq Er DW_DLE_MEMORY
An out of memory condition was encountered during the execution of the
function.
.El
.Sh SEE ALSO
.Xr dwarf 3 ,
.Xr dwarf_attr 3 ,
.Xr dwarf_dealloc 3 ,
.Xr dwarf_hasattr 3 ,
.Xr dwarf_hasform 3 ,
.Xr dwarf_whatattr 3 ,
.Xr dwarf_whatform 3
